Grapevine growers embrace certification

Certification percentages of grapevines put the pome- and stone-fruit industries to shame. Fresh Quarterly spoke to leading vine nurserymen to learn more. By Anna Mouton.

About 82% of the nearly 17 million grapevines produced by nurseries in 2022 were either certified or had candidate status — compared to approximately a third of pome- and stone-fruit trees. The wine industry can take credit for pioneering plant improvement in viticulture, but table and drying grapes are catching up.

“People in the wine industry set great store by the certification status of vines — they have become used to certain standards for vines,” says Theo Heydenrych Snr. He should know: he is a third-generation nurseryman himself. He also chairs the Vine Improvement Association and the South African Vine Growers Association. The latter was founded in 1964.

The Heydenrych family owns Hexberg Nursery in Wellington. About 90% of their vines are wine grapes, and the rest are table and drying grapes. Hexberg is also registered as a Plant Improvement Organisation.

“In 2024, our business will be 100 years old,” reflects Heydenrych Snr. “The fourth generation in our business deals with the fourth generation of our clients.”

In addition to sustaining their long-standing client relationships, Theo Heydenrych Jnr represents the South African Vine Growers Association on the Vine Improvement Association Technical Committee, while Hexberg colleague Divan Venter, who manages marketing and supports growers, represents the Hexberg Plant Improvement Organisation.

Vine growers unite

Plant improvement in the wine industry started through individual nurseries selecting better vines and setting product standards. The current Vine Improvement Association was established in 1986, and the Plant Certification Scheme for Wine Grapes was promulgated in 1992 under the Plant Improvement Act 53 of 1976.

In those days, Wellington was the Mecca for vine nurseries, supplying almost all the vines planted in the wine industry, says Heydenrych Snr. “Wellington nurserymen organised themselves in a vine-growers association and collaborated with the KWV. The KWV was the main plant-material supplier. Imported material came to Nietvoorbij — the Agricultural Research Council — and they cleaned and multiplied it.”

The wine industry was deregulated after 1990, but the Vine Improvement Association continued to flourish. In 2017, table and drying grapes were moved from the Deciduous Fruit Plant Certification Scheme to what is now known as the South African Plant Certification Scheme for Vitis.

Heydenrych Snr points out that industry buy-in took time. “Try telling a farmer what to do on his own land — there was conflict. But that has changed completely. The different role players now support each other to maintain what we’ve built up and to take the industry forward.”

Wine-grape economics

Wine producers are wary of planting infected material because the margins on wine grapes are so small, says Heydenrych Jnr. “That vine needs to stay in production for at least 15–20 years to recoup the money spent on it, so growers can’t afford to plant infected material and lose 2–3 years of its lifetime.”

Grapevine leafroll-associated viruses are the main challenge — infections debilitate vines and reduce grape yields and quality. In addition to spreading through infected plant material, these viruses are also transmitted by insects.

“Leafroll is enemy number one,” says Heydenrych Snr, “but in the wine industry, certified material is as close to 100% clean as it’s possible to get. It’s so well-managed that I never wonder whether material I receive from a Plant Improvement Organisation is infected.”

Heydenrych Jnr is quick to highlight that this wasn’t always the case. “It took 20 or 30 years, and it only happened because we always followed the plant improvement process. If you stick to the rules, the plant material eventually becomes clean.”

In addition to leafroll-associated viruses, certified plant material is tested for viruses that cause fanleaf, fleck, corky bark, and stem-pitting and Shiraz disease.

Freedom from viruses is not the only reason wine producers prefer certified material, says Heydenrych Snr. Varietal assessment and correct identity also carry weight. “Yields are very important in the wine industry, and you’re not going to get there if you plant a substandard vine or the wrong cultivar.”

Table-grape timelines

At 48% vine certification, the table-grape industry lags far behind wine and drying grapes — although it still beats most pome and stone fruit hands down. “Cultivar turnover in the table-grape industry is incredibly high,” says Venter, “and many of those new cultivars are uncertified, but producers want them.”

New cultivars imported to South Africa must be free of quarantine pests and diseases, so they either arrive as tissue-cultured plants or endure a stint in quarantine. Plant Improvement Organisations then establish the vines in enclosed nucleus units where they undergo thermal therapy and testing for scheme viruses and pests.

A small number of vines propagated from nucleus plants are subsequently grown outside in foundation units. This is where varietal assessment occurs, with the aim of registering the cultivar on the official varietal list.

Although there are ways to speed up the process — for example, propagating and selling candidate material while certification is underway — table-grape growers may still feel that they’re losing out on marketing opportunities, explains Venter. “The producer wants to plant now because then he’s the first person to pack and ship that cultivar and make money — he’s not too worried about the colour of the tag on that vine.”

Heydenrych Jnr has seen this impatience backfire in wine grapes. “There was a time when everyone wanted red cultivars and used any budwood — even uncertified material. Some of our clients can show us vineyards that were planted with infected material then and that have leafroll and other diseases now.”

When it comes to certification, Heydenrych Jnr is a true believer. “We must always remember to follow the processes because every small thing has value. You reach a point when all the material is so clean that you wonder why we still bother — but it’s precisely because we continue implementing our plant certification scheme that our plant material remains clean.”

Image: Theo Heydenrych Jnr and Snr.

Supplied by Anna Mouton.